This invention is directed to a shifting arrangement for, and a method of shifting, a manual transmission, and more particularly to a shifting arrangement having a shift rotor which can adjust shifting elements by way of coupling elements.
A shifting arrangement of this type is described, for example, in Mueller (U.S. Pat. No. 5,433,125) and has a shift rotor whose rotation shifts six forward gears and one reverse gear. The shift rotor is provided with guideways in which intermediate elements engage which interact with shift forks in a manner known per se. By means of the longitudinally guided intermediate elements, the rotating movement of the shift rotor is converted into a longitudinal movement of the shift forks. The rotating movement of the shift rotor is triggered by a step-by-step system which is connected with the shift lever of the motor vehicle. For shifting the forward gears and the reverse gear, the shift lever is moved in a single shifting channel. By moving the shift lever from a central neutral position into a shifting direction, an upshifting is triggered and by moving the shift lever from the neutral position into the opposite direction, a downshifting is triggered. In order to prevent an unintended shifting from the first gear into the reverse gear, a locking device arranged on the shift lever is provided which, by way of a cable pull, acts upon a detent pawl on the shift rotor. Furthermore, the manual transmission can be brought from each shifting position into a neutral shifting position by a transverse movement of the shift lever. In this case, a shift fork, which cooperates in the shifting of all transmission gears including the reverse gear, is provided with a swivellable coupling element which can be swivelled out of the guide of the intermediate element and can be brought into a neutral position by means of an additional guide. This swivelling out takes place by means of a servo motor which cooperates in each shifting operation and in the transverse movement of the shift lever.
An object of the present invention is to improve a shifting arrangement and method of the type generally described above such that the protection against an unintentional engagement of the reverse gear is increased and simultaneously the entire shifting arrangement can be operated with out servo motors.
This and other objects have been achieved according to the present invention by providing a shifting arrangement for a manual transmission having a plurality of forward gears and at least one reverse gear, the shifting arrangement comprising: a shift lever movable in a first shifting channel, movable in a second shifting channel, and movable between the first and second shifting channels, at least the reverse gear being shifted by movement of the shift lever in the second shifting channel; a shift rotor operatively coupled to the shift lever by way of a first transmitting device such that the shift rotor is rotatable by movement of the shift lever in the shifting channels; a plurality of shifting elements operatively coupled to the shift rotor by way of respective coupling elements; and a preselection device operatively coupled to the shift lever by way of a second transmitting device such that movement of the shift lever between the first and second shifting channels is transmitted to the coupling elements.
This and other objects have also been achieved according to the present invention by providing a method of shifting a manual transmission having a plurality of forward gears and at least one reverse gear, a shift lever movable in a first shifting channel, movable in a second shifting channel, and movable between the first and second shifting channels, a shift rotor operatively coupled to the shift lever by way of a first transmitting device, a plurality of shifting elements operatively coupled to the shift rotor by way of respective coupling elements, and a preselection device operatively coupled to the shift lever by way of a second transmitting device, the method comprising the steps of: moving the shift lever in the first shifting channel to shift between the forward gears by way of the first transmitting device, the shift rotor, the coupling elements, and the shifting elements, moving the shift lever between the first and second shifting channels to rotate the preselection shaft and the coupling elements to a neutral position; and moving the shift lever in the second shifting channel to engage and disengage the reverse gear by way of the first transmitting device, the shift rotor, the coupling elements, and the shifting elements.
A very high protection against faulty shifting and unintentional shifting of the reverse gear is achieved in that the forward gears of the manual transmission are shifted by moving the shift lever in a first shifting channel. Independently of this first shifting channel, the reverse gear is shifted in a second shifting channel so that a momentary separation of the shifting function exists for the driver. For engaging the reverse gear or for preselecting the reverse gear channel, the shift lever is moved perpendicularly to the first shifting channel. For this purpose, the shift lever is coupled by way of second transmitting devices with a preselection shaft by means of which coupling elements can be adjusted between the shift fork and the shift rotor. The adjustment of the coupling elements therefore takes place independently of the position or operation of the shift rotor. A shifting arrangement is therefore created in which a secure separation is provided between the operation of the forward gears and the operation of the reverse gear and which the driver can easily carry out when operating the shift lever. In this case, the shifting arrangement can be operated without any support by servo motors which permits considerable savings with respect to components and, in particular, a high-expenditure electronic control system is not necessary.
A shifting arrangement of this type can be constructed in a particularly space-saving manner if the coupling elements are longitudinally guided on the preselection device constructed as a preselection shaft and can be adjusted approximately perpendicularly thereto by means of the second transmitting devices. In this case, the coupling elements can be guided on this preselection shaft in the shifting direction, this movement being caused by the rotation of the shift rotor. The second transmitting devices coupled with the preselection shaft can then advantageously swivel the coupling elements by the rotation of the preselection shaft approximately perpendicularly to the shifting direction.
A particularly advantageous construction of the shifting arrangement is obtained if, during the swivelling by means of the second transmitting device, the coupling elements interact with an adjusting unit which permits a forcedly guided displacement of the coupling elements in the shifting direction. Thus, already during the swivelling of the coupling elements, a shifting operation can be carried out which changes the respective shifting element either into a neutral position or into a reverse-gear position.
It is also possible to construct the coupling element such that it is coupled with the shift rotor by means of two spaced guide members in the respective end positions of the swivel movement. As a result, by means of the first guide member in the first end position of the swivel motion, a shifting movement for the forward gears can be carried out while, by means of the second guide member, in the second shifting channel, the shifting movement for the reverse gear is carried out.
The shifting operation by means of such a shifting arrangement will still be considerably safer if, in addition, locking devices are provided by means of which a shifting of the reverse gear is possible only from defined shifting positions of the manual transmission. As a result, it can be ensured that an engagement of the reverse gear is possible only if the first gear was engaged before.
This locking device can advantageously consist of interacting locking members between the preselection shaft and the shift rotor. In a space-saving manner, these may be arranged inside the shifting arrangement or inside the transmission, in which case a purely mechanically operating lock is conceivable. In a particularly advantageous manner, the locking members may consist of at least one locking disk respectively on the preselection shaft and the shift rotor and of one locking member interacting with these.
These and other objects, features and advantages of the present invention will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.